Preparation of ynamines and phenylacetamides

ABSTRACT

A METHOD FOR PREPARING YNAMINES AND HENYLACETAMIDES COMPRISES CONTACTIN PHENYLACETYLENES WITH PRIMARY OR SECONDARY AMINES IN THE PRESENCE OF COPPER AND MOLECULAR OXYGEN TO PRODUCE THE YNAMINE, AND THEN TREATING THE CRUDE MIXTURE WITH AQUEOUS ACID TO PRODUCE PHENYLACETAMIDE. WHEN SECONDARY AMINES ARE USED IN THE PRECEDING REACTION, THE YNAMINES CAN BE ISOLATED AND RECOVERED.

United States Patent 3,657,343 PREPARATION OF YNAMINES ANDPHENYLACETAMIDES Laurence I. Peterson, Midland, Mich., assignor to TheDow Chemical Company, Midland, Mich.

No Drawing. Original application Aug. 24, 1969, Ser. No. 662,865.Divided and this application Aug. 27, 1969, Ser. No. 870,964

Int. Cl. C07c 103/30 US. Cl. 260-558 R 2 Claims ABSTRACT OF THEDISCLOSURE A method for preparing ynamines and phenylacetamidescomprises contacting phenylacetylenes with primary or secondary aminesin the presence of copper and molecular oxygen to produce the ynamine,and then treating the crude mixture with aqueous acid to producephenylacetamide. When secondary amines are used in the precedingreaction, the ynamines can be isolated and recovered.

This application is a division of my US. Patent 3,499,- 928, filed Aug.24, 1969.

BACKGROUND OF THE INVENTION My invention is a process for oxidizingphenylacetylenes in the presence of secondary amines, with copper as acatalyst, to yield recoverable ynamines, and further, with an aqueousacid addition, the corresponding phenylacetamides. When a primary amineis reacted with phenylacetylenes, the resultant ynamine is continuouslyhydrolyzed to the corresponding phenylacetamide without the addition ofacid, and the ynamine is not recoverable.

The previously known processes for producing ynamines make use of thereaction of haloacetylenes, or compounds which yield haloacetylene insitu, which lithium amides. These reactions necessitate using diflicultto handle and difi'icultly accessible starting materials. Also requiredare low temperatures of around -70 C. to control the vigorouslyexothermic reactions which result.

The hydration of ynamines to phenylacetamides is reported by Wolf andKowitz (Annalen Der Chemie, 638 33 (1960) However, this method requiredthe production of ynamines in one step, their isolation, and finalconversion, in another step, to the corresponding phenylacetamide.

SUMMARY OF INVENTION The method of the invention comprises reacting bycontacting a phenylacetylene, which may be ring substituted with one ormore inert substituents, with a primary or secondary alkyl amine andmolecular oxygen, in the presence of a copper catalyst. At theconclusion of this reation, water is added, and, if a secondary aminehas been used, the ynamine can be separated. However, an aqueous acidcan be added in lieu of water at this point, and the ynamine will bereadily hydrated to the corresponding phenylacetamide.

If a primary amine be used in the above, although the ynamine isprobably formed, it cannot be recovered, as it is too readily hydratedto the corresponding phenylacetamide. The latter, then, is the onlyproduct isolated.

A preferred embodiment of the above is a method for the preparation ofynamines (STRUCTURE I) and phenylacetamides (STRUCTURE II) STRUCTURE ISTRUCTURE II 3,657,343 Patented Apr. 18, 1972 wherein R" is hydrogen oran inert substituent, such as analkyl, preferably from 1 to 8 carbonatoms, such as methyl, butyl or octyl; a phenyl; an alkoxy, preferablyfrom 1 to 8 carbon atoms, such as methoxy, butoxy or octoxy; a phenox oran inert halogen, as fluorine or chlorine, with an amine of the formulaRRNH, R and R' as defined above, in an inert solvent, such as benzene ormethanol, or in an excess of the amine, and molecular oxygen, in thepresence of a copper salt capable of producing Cu+ or Cu++ ions toproduce Structure I. The molar ratio of the copper catalyst tophenylacetylene is not critical and can vary from about 1.0 to 0.0001,and is preferably from about 0.05 to 0.2. The molar ratio of amine tophenylacetylene suitably should be greater than 1.0, and most preferablyabout 10.0. The temperature can vary from about 40 to C., and mostpreferably is from 0 to 40 C. And the reaction time, although notcritical, is most desirably from about 5 to 30 minutes. Atmosphericpressure is adequate, although increasing the oxygen pressure above oneatmosphere has a slightly favorable effect.

Addition of an aqueous acid to the crude reaction mixture results inhydration of Structure I to Structure II.

This method also comprises reacting a phenylacetylene of the sameformula as above with a primary amine in the same reaction environmentas described above. This reaction produces an intermediate which whencontacted with water is converted to an amine of Structure II, andcannot be separately recovered.

SPECIFIC EMBODIMENTS Following are specific examples of my invention,although they are in no way intended to limit same:

Example I.--Oxidation of phenylacetylene in the presence ofdimethylamine Phenylacetylene (5.1 g., 0.050 mole) in ml. of benzene wasadded dropwise over one-half hour to a stirred solution of 2.0 g. (0.010mole) of cupric acetate monohydrate dissolved in 25 ml. of dimethylamineand 100 ml. of benzene at 0 C. A stream of oxygen was continuouslypassed through the reaction mixture during addition of thephenylacetylene and for 30 minutes thereafter. Water (50 ml.) was thenadded to the reaction mixture to precipitate the copper salts. Thecolorless benzene layer was washed twice with 50 ml. of water and thenfiltered and dried over calcium sulfate. Dimethylaminophenylacetylenewas then isolated by removing the benzene under vacuum and by allowingthe coproduced diphenylbutadiyne to crystallize from solution at 0 C.The resulting liquid was shown to be the ynamine by comparing itsinfrared and N.M.R. spectra with authentic material. The N.M.R. spectrumrevealed resonance peaks (CCl at 2.73 ppm. and -7.14 p.p.m. in a 6:5ratio, respectively, whereas the infrared spectrum exhibited a veryintense doublet at 2200 and 2230 cm.-

Gas chromatographic analysis of the crude product revealed that thephenylacetylene was quantitatively converted into product and that thecrude reaction product consisted of 58% ynamine and 42%1,4-diphenylbutadiyne.

Example II.-Oxidation of phenylacetylene in the presence ofdimethylamine When the reaction was conducted as described in Example I,except that the reaction mixture is worked up with dilute hydrochloricacid instead of water, the prodnet is N,N-dimethylphenylacetamide sincethe ynamine is readily hydrated in the presence of aqueous acids.

Example III.Oxidation of phenylacetylene in the presence of ethylamineOxygen was bubbled through a solution of 10.0 g. (0.05 mole) of cupricacetate monohydrate in 300 ml. of anhydrous ethylamine at 0-5 C. To thisreaction mixture was added dropwise a solution of 25.5 g. (0.25 mole) ofphenylacetylene in 325 ml. of benzene over a two hour period. Thereaction mixture was worked up as in Example I, to give a product whichcontained Nethylphenylacetamide.

The following table shows the results of various experiments whichexemplify my invention. A comparison of the conversion percentage andthe ynamine/dimer ratio essentially expresses 100% of the reactants andproducts. The ratio of the secondary amine to phenylacetylene Was 20.0in all cases. The concentration of the catalyst is expressed in molesper liter, While the ynamine/ dimer ratio is expressed as moles ofynamine per mole of 1,4-diphenylbutadiyne.

4 I claim: 1. A method for the preparation of a phenylacetamide of theformula which comprises reacting by contacting with molecular oxygen, ata temperature of from about 40 to 80 C. and in the presence of acatalytic amount of a soluble copper salt that is capable of producingCu+ or Cu++ ions, a phenylacetylene of the formula Cone. of

Experiment number Amine Solvent Catalyst catalyst Oxygen Reactionpressure, temp., mm. C.

Conversion percent Ynamine/ dimer 80 Dimethyl- Benzene Cu(OAc)z Diethyldo Cu( 103 do H .152 17813 Dimethyl- Toluene... C11(OAC)2 ReferencesCited UNITED STATES PATENTS 9/1967 Viehe 260-1l2.5

HENRY R. JILES, Primary Examiner H. I. MOATZ, Assistant Examiner US. Cl.X.R.

260558 HL, 559 R

